Gather metrics classifying the cause of the TLS fallback.

net/socket/socket_test_util.cc

Index: net/socket/socket_test_util.cc
diff --git a/net/socket/socket_test_util.cc b/net/socket/socket_test_util.cc
index cf033c245c3e86c8b5c427c2dc061e49172b7a3a..8a26531aa76f9c9039a202ee8ebb554bbfd07b92 100644
--- a/net/socket/socket_test_util.cc
+++ b/net/socket/socket_test_util.cc
@@ -26,6 +26,7 @@
 #include "net/socket/websocket_endpoint_lock_manager.h"
 #include "net/ssl/ssl_cert_request_info.h"
 #include "net/ssl/ssl_connection_status_flags.h"
+#include "net/ssl/ssl_failure_state.h"
 #include "net/ssl/ssl_info.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -1029,6 +1030,10 @@ ChannelIDService* MockClientSocket::GetChannelIDService() const {
   return NULL;
 }
 
+SSLFailureState MockClientSocket::GetSSLFailureState() const {
+  return IsConnected() ? kSSLFailureNone : kSSLFailureUnknown;
+}
+
 SSLClientSocket::NextProtoStatus MockClientSocket::GetNextProto(
     std::string* proto) const {
   proto->clear();